Research Collection
Book Review
Philosophy and Climate Science by Eric B. Winsberg
Cambridge University Press, 2018, 282 pp., ISBN 9781316646922
Author(s):
Knüsel, Benedikt Publication Date:
2020-02
Permanent Link:
https://doi.org/10.3929/ethz-b-000351329
Originally published in:
Ethics, Policy & Environment 23(1), http://doi.org/10.1080/21550085.2020.1733299
Rights / License:
In Copyright - Non-Commercial Use Permitted
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Eric Winsberg: “Philosophy and Climate Science”
This book review has been accepted for publication in Ethics, Policy & Environment, published by Taylor & Francis.
Benedikt Knüsel
Institute for Environmental Decisions, Institute for Atmospheric and Climate Science ETH Zürich
benedikt.knuesel@usys.ethz.ch
Climate change is a ubiquitous topic these days. Temperature records and extreme weather events frequently make the news. And in the spring of 2019, millions of youth activists have organized protests all over the world to demand more ambitious climate policy. Often, these calls for climate action were accompanied by the demand that policy-makers listen to the scientists. Indeed, climate science is a highly policy-relevant research area (which, of course, does not imply that “listening to the scientists” is sufficient to justify policy decisions, see Evensen 2019). If we, as a society, want to base our decisions about the climate on the best available scientific knowledge, we need to understand not only what scientists tell us, but also how they arrive at their conclusions and what reasons we have to trust them. This is where philosophy of climate science enters the stage, and this is why Eric Winsberg’s book
“Philosophy and Climate Science” is such a timely piece.
Winsberg’s book is an introduction to the young field of philosophy of climate science. It is targeted primarily at philosophers of science, but it is intended to be accessible also for climate scientists and a wider general audience. This is an ambitious goal as it needs to introduce the readers to the complex, interdisciplinary field of climate science and raise questions of philosophical interest about this research. “Philosophy and Climate Science”
approaches this difficult task in three parts. The first part discusses the methodology of climate science (chapters 2 – 5), the second part is about uncertainty (chapters 6 – 9), and the third part is about epistemological issues (chapters 10 – 13). Winsberg’s good understanding of climate science and his accessible style of writing make the book a very good introduction to the topic. Most parts are convincing and do a good job of introducing a wide audience to relevant philosophical questions about climate science. This is especially true of the
methodological and the epistemological part. The respective chapters are informative and bring together the scientific and philosophical questions in an accessible, illustrative way.
In the following, I briefly outline the content of each chapter. Chapter 2 focuses on data used in climate science. Winsberg introduces topics from philosophy of science relating to data, namely models of data and the fact that scientific hypotheses can only be tested with the help of auxiliary hypotheses (the so-called Quine-Duhem problem). These philosophical tools can help to understand scientific issues, as is illustrated with the discussion of a case study about model-data discrepancy. Winsberg closes the chapter by listing different datasets used as evidence of a warming planet. This list is likely not detailed enough to introduce readers to
Chapter 3 uses a simple energy-balance model to introduce climate models. The focus of the philosophical discussions is on different kinds of idealizations and the notion that climate models should be evaluated in terms of their adequacy-for-purpose rather than their
representational accuracy. Based on this discussion, Winsberg shows that the question how good a climate model is has no simple answer: it depends on the purpose and the desired level of accuracy.
In chapter 4, the reader is introduced to complex climate models used for computer
simulations. Based on a clarification of what simulations are, Winsberg turns to some general purposes of simulation models and introduces the notion of climate projections (i.e., a
prediction that is conditional on a forcing scenario). In order to clarify how climate
projections are made, the chapter discusses different features of climate models, from a set of partial differential equations to a final model implemented on a computer that can be used for running simulations. While this chapter engages less explicitly with philosophical concepts compared to the other introductory chapters, it provides very good groundwork for what is to follow in the book.
Weather predictions are not reliable beyond the range of several days, and the reason for this is that the Earth’s atmosphere shows chaotic behavior. Chaos and how it affects climate projections is the topic of chapter 5. While this chapter is more technical and hence less accessible than the previous ones, it is worth reading. Winsberg shows why climate projections are not affected by the chaotic behavior of the atmosphere in the same way as weather predictions. This is because external forcing can lead to predictable patterns in a chaotic system, as Winsberg illustrates.
Chapters 6 and 7 discuss the topics of uncertainty. The first of these two chapters introduces the difference between chances (or objective probabilities) and credences (or subjective probabilities) and convincingly argues that probabilities in climate science can only be understood as credences. Winsberg concludes that probabilities are the best tool for climate scientists when communicating uncertain information to policy-makers. The second of these two chapters discusses how climate scientists obtain probability estimates. For this, the chapter discusses different sources of uncertainty, which follows nicely from the introductory chapters on models and simulations. In order to quantify uncertainty from these sources, climate scientists employ two methods, namely model ensembles and expert judgment, which, as Winsberg argues, should ideally be combined. Besides these probability estimates, which the Intergovernmental Panel on Climate Change (IPCC) calls “likelihoods”, IPCC reports also routinely state what level of confidence there is about propositions. Based on the sections about the methods for estimating uncertainties, Winsberg discusses how this confidence metric relates to the likelihood scale. Namely, the likelihood scale should be used to express credences, and the confidence scale should be used to assess the process of arriving at the credence statements, i.e., as a second-order assessment. Given the inconsistencies in the use of the two metrics in the IPCC reports, this is a good starting point for much needed further work on this topic.
Chapter 8 turns to decisions. It is the only chapter of the book without an introductory section, and unfortunately, this lack of framing makes this chapter somewhat difficult to follow. The chapter introduces the classical statistical approach and the Bayesian approach of statistical inference. Many of the explanations might not be necessary for readers with a background in statistics, but they might also be too challenging for readers for whom the topic is new.
Winsberg makes the convincing point that climate science and climate policy need to develop new decision frameworks and that this is an area where philosophers can contribute. The last section of the chapter provides a helpful discussion of cost-benefit analysis in the context of so-called integrated assessment models, which is interesting but largely independent of the preceding sections. Such models aim to base political decisions regarding the climate on scientific considerations by optimizing welfare in a model of the economy that is coupled to a simple climate model. Winsberg shows that such attempts are fraught with assumptions that are difficult to justify, regarding for example the choice of the discount rate, the form of a damage function, and the measure of welfare.
In chapter 9, Winsberg discusses the value-free ideal of science, i.e., whether non-epistemic values play a role when scientists accept or reject hypotheses. He argues that it is especially difficult to live up to the value-free ideal in model-intensive scientific fields because of the complexity of the models, the distributed epistemic agency, and the predictive preferences of researchers who develop or change models. Many of the points the chapter makes follow from earlier discussions of simulations, but they are a bit repetitive for readers who read the book from the beginning to the end. Also, a clearer separation between social and ethical values on the one hand and pragmatic considerations for certain modeling choices (see Parker 2014) would have made this chapter clearer.
The book returns to climate models and simulations more explicitly in chapter 10, for a discussion of model skill. The focus of the chapter is largely on parameterizations and on model tuning (the process in which the best parameter values are chosen). The models are tuned to observational data, and it is unclear to what extent the same data can also be used to evaluate model skill. Winsberg offers a good recap of this debate and argues that novel data offers a stronger test of model skill than data that was used for tuning.
Chapters 11 and 12 discuss robustness analysis in climate science. Chapter 11 introduces the philosophical debate about robustness analysis in climate science. In chapter 12, Winsberg turns to diversity of evidence and makes a novel, convincing suggestion for when multiple sources of evidence in favor of a hypothesis are meaningful in climate science. Namely, they are useful if they help to rule out rival explanatory hypotheses. This discussion is illustrated both with an intuitive example from everyday life and with an example from climate science, namely estimating the value of equilibrium climate sensitivity (which indicates by how much, in the long run, the average temperature on Earth would warm in response to a sustained doubling of the atmospheric CO2 concentration). These two chapters are not only interesting, but also very fruitful for further work in philosophy of climate science.
In the final chapter, Winsberg discusses three topics from social epistemology and what they
They discuss why a consensus in the scientific community about the anthropogenic origin of climate change can be meaningful to laypeople, and why dissent in the scientific community can be epistemically detrimental.
“Philosophy and Climate Science” covers a lot of ground and focuses on the most relevant issues. It will hence be a useful resource for most readers. Throughout the book, there are boxes containing additional information, which are both interesting and often nicely
complement the main text. Each chapter also contains recommendations for further reading where readers can find an in-depth discussion of the main topics. I particularly enjoyed the chapters which illustrated why philosophical discussions are important for climate science without long detours through other material. This is especially true of chapters 2 (“Data”), 12 (“Diversity”), and 13 (“Social Epistemology”). The book is a great starting point for future research as it got me thinking about several potential research projects that would not only be philosophically interesting but would also advance climate science. For example, the
discussions about data models discussed in chapter 2 and about model tuning in chapter 10 have direct consequences for the independence of simulation results and observational data.
To what extent observations and simulations can complement each other in robustness analysis (chapters 11 and 12) should thus be clarified. The book also contains good suggestions for the treatment of uncertainty in the IPCC reports that could help to better separate the notions of likelihood and confidence.
The less convincing parts of the book are those in which the discussion is less focused on climate-specific points. This mainly concerns the second part on uncertainty, and particularly sections of chapters 6 (“Probability”) and 8 (“Decisions”). However, the topics of these chapters are undeniably of great importance. There are also issues that might have deserved attention that are not part of the book. For example, I would have enjoyed a brief discussion of conceptual issues such as how to define “climate” and how to determine which factors are considered internal or external to the climate system (e.g., anthropogenic greenhouse gas emissions, see Katzav and Parker 2018).
Eric Winsberg has written a book worth reading for philosophers of science and for climate scientists alike. I am sure that reading it will be beneficial also to researchers from other communities with an interest in the topic, even though not all chapters might be equally accessible to them. “Philosophy and Climate Science” is a lucid and timely book that will shape work in the philosophy of climate science in the years to come.
Book: Winsberg, Eric B. 2018. Philosophy and Climate Science. Cambridge, United Kingdom ; New York, NY: Cambridge University Press.
References
Evensen, Darrick. 2019. “The Rhetorical Limitations of the #FridaysForFuture Movement.”
Nature Climate Change 9: 428–430. https://doi.org/10.1038/s41558-019-0481-1.
Katzav, Joel, and Wendy S. Parker. 2018. “Issues in the Theoretical Foundations of Climate Science.” Studies in History and Philosophy of Modern Physics 63: 141–49.
https://doi.org/10.1016/j.shpsb.2018.02.001.
Parker, Wendy. 2014. “Values and Uncertainties in Climate Prediction, Revisited.” Studies in History and Philosophy of Science 46: 24–30. https://doi.org/10.1016/j.shpsa.2013.11.003.
